#include <iostream>
using namespace std;

//https://ac.nowcoder.com/acm/problem/222104

const int N = 1e5 + 10;
int n;
char s[N];
char ret[N];


int main()
{
    cin >> n >> s;
    int hash[26] = { 0 };

    int maxIndex, maxCount = 0;
    for (int i = 0; i < n; i++)
    {
        if (++hash[s[i] - 'a'] > maxCount)
        {
            maxCount = hash[s[i] - 'a'];
            maxIndex = s[i] - 'a';
        }
    }

    if (maxCount > (n + 1) / 2) cout << "no" << endl;
    else
    {
        cout << "yes" << endl;
        int index = 0;
        while (maxCount--)
        {
            ret[index] = maxIndex + 'a';
            index += 2;
        }

        for (int i = 0; i < 26; i++)
        {
            if (hash[i] && i != maxIndex)
            {
                while (hash[i]--)
                {
                    if (index >= n) index = 1;
                    ret[index] = i + 'a';
                    index += 2;
                }
            }
        }

        for (int i = 0; i < n; i++) cout << ret[i];
        cout << endl;
    }



    return 0;
}